The present invention relates to electrical grounding devices and, more particularly, to an universal clamp used in coupling rods, pipes or other structures of various cross-sections to ground mechanisms.
In many instances, there is a need to provide an electrical coupling to structures of various sized and shaped cross-sections for grounding purposes. These instances include grounding of pipes, conduit, and other structures of mechanical and/or electrical systems to dissipate electrical charge to protect the systems and/or individuals who may come in contact with the components of such systems. Grounding clamps are commonly employed for these purposes.
Grounding clamps come in a variety of configurations and use various means for forming a conductive attachment. One type of clamp includes a metal strap with a plurality of holes, a metal stud, and conventional nuts to secure the strap about the periphery of the structure. More specifically, the metal strap encircles the structure and the threaded stud is inserted through two of the holes to secure the metal strap tightly around the periphery of the structure. The metal strap is drawn tightly around the periphery of the structure as the nut is tightened on the bolt. The clamp typically includes a ground terminal to which a wire is attached for connecting the clamp to a conventional ground mechanism, such as a ground rod. Strap type clamps accommodate different diameters of pipes or conduits or cross-sections of other shaped structures, such as boxes. This adaptability to a variety of structures eliminates the need for an inventory of grounding clamps that are specifically designed for a specified structure.
Strap-type clamps typically use nuts with sharp edges. These sharp edges are known to gouge the metal strap as the metal strap is tightened at the stud. This gouging causes creases and areas of weakness which severely shortens the overall life of the strap and can limit the effectiveness with which it conducts electricity.
One solution to gouging, or otherwise providing a non-destructive tightening of the strap, is disclosed in my U.S. Pat. No. 4,626,051, which discloses the use of two nuts, each having a smooth curved surface for engaging the strap. The curvature of the surface better accepts the angle of the metal strap as it leaves the various structures and attaches to the stud. While this advancement successfully prevents the gouging of the strap by eliminating the sharp edges of the engagement, one of the nuts must be removed from the stud during installation, and this leads to the possibility of losing the nut and/or lost time retrieving (if even possible) the lost nut. This situation is compounded by the fact that many installations are made in awkward and sometimes dangerous locations, such as those to suspended systems requiring installers to use scaffolding, catwalks and/or ladders to reach the suspended structures.
Another problem associated with existing strap-type grounding clamps is that the stud must be thread through the initial hole it is fed through in the metal strap in order to prevent the stud from coming apart from the strap, (e.g., in order to prevent the stud from becoming lost). Unfortunately, the threading of the stud through the hole of the strap increases installation time and keeps the installer in the awkward or dangerous positions required to install the clamp, (e.g., scaffolding, catwalks, ladders, etc.), longer than he or she need be. Alternatively, existing strap-type grounding clamps may be provided with holes through which the stud easily passes; however, such configurations are unacceptable because they increase the likelihood that the stud will be lost and/or increase installation time due to lost time retrieving (if possible) the lost stud.
Thus, the present invention addresses the need for an entirely self contained universal clamp that eliminates loose parts and the need for a more efficient method and apparatus for installing universal grounding clamps.